Safety block



Jam., l940. M, P PALSSQN Z SAFETY BLOCK Filed NOV. 4, 1938 INVENTOR.'

Patented Jan. 16, 1940 K UNITED STATES PATENT oFFicE SAFETY BLOCK `Magnus P. Palsson,` Seattle, Wash. Application November 4, 1938, Serial No. 238,880

3 Claims.

sent a novel linev brake device adapted to be incorporated upon sheave blocks, operative in such manner that it may be controlled by the hauling line to either hold a rope or other line against movement by the load when its outer or hauling end is released, and to alloweither further hoisting, or paying out of the rope for lowering of the load at will. I

An important aim of the invention is to present a simple construction in such a .device embodying novel features contributing to efficiency and durability of such appliance.

Additional objects, advantages, and features of the inventionreside in the construction, arrangement and combination of parts involved in the embodiment of the invention, as will be understood from the following description and accompanying drawing, wherein Figure 1 is a side view of one embodiment of the invention in a sheave block suitable for handline and other hoists with one of the cheek plates broken away.

Figure 2 is a front view of the block at the side of the hoist line; I.

Figure 3 is a bottom View of the article with the line-anchor-eye and itssupport broken away.

Figure 4 is a fragmentary section of a particular structure of dog; I

Figure 5 `is a fragmentary elevation from the right of Figure 2, with parts broken away showing the operating pin of the dog and its slot in the cheek plate.

There is illustrated a strap frame I0, substantially inthe form of an inverted U, a suspension hook II` being swivelled in the bight I2, and the lower extremities of the arms having a bar I3 thereacross on which is suspended pivotally a line-anchor-eye I4.

A sheave shaft I5 is fixed between the arms of the frame II) intermediately of the height of the frame, on which sheaves I6 of the common grooved form are revoluble, cheek plates I'I being interposed respectively between the two sheaves and between the sheaves and the respective side members of the frame. The cheek plates are also connected to the frame IllV by upper and lower assembly bolts I8 and I9, the first `engaged through upper extensions Il of the cheek plates and in the sides of the frame I0, and the one I9 engaged through the lower portions of the cheek plates and the arms of the frame Ill, just above the shaft I3. Between the right hand cheek plate I1 and the adjacent side member of the (Cl. 18S-651) frame IIJ, there are washerslZIl, by which this cheek plate is spaced from the frame.

On the bolt IB a cable-locking dog 2I` is loosely pivoted to swing into close proximity to the right hand sheave It, the dog being formed with a transversely ridged or otherwise roughened cam face,`the normally forward part of which is of greater radius than its rear part', and" suitably curved so that large and small cables willA be properly gripped when drawn thereunder and over the sheave from left to right as `viewed in Figure l. In such movement of a cable, the dog will grip the upper side of the cable and be drawn `with the cable toward the sheave until it so wedges against the cable as to stop its further movement. In order to make certain the movement of the dog into engagement with a cable, it is spring-loaded so as to be pressed toward locking position. Also, means is provided operable by the same rope which engages the dog to control the function of the dog.

The spring loading of the dog consists of an operating pin 22 or shaft xed transversely through the dog a distance from its pivot I8, and projectedthrough suitable slots 23 in the adjacent cheek plates concentric with the bolt It. The operating pin is tenoned at its ends and provided with roller sleeves 24 working thereon in the slots 23. The leftend of the pin is extended and journalled in an eye bearing 25 formed on the end of a connecting rod 2li which is extended rearwardly therefrom, its ear bent at right angles and engaged revolubly in an eye bearing 2l of a rod 28 extending horizontally forward and engaged slidably through a guide ear 2d formed on the forward part of the upper extension il of the extreme left hand cheek plate Il. The rod 23 is of sufficient length to remain always engaged through the ear 29. A protractile helical spring 30 is engaged around the rod 28, confined between the ear 29 and bearing 2l on the rod 28 in advance of the bearing 2l, by which means the pin 22 is forced towardthe rear, carrying the dog, which isthus held yieldingly in engaging relation to the sheave or interposed.v

cable. l

For operating and controlling the dog ZI, two sector-shaped lever plates 3l of identical form and size are pivoted on the shaft I5 between the right hand sheave I5 and respective cheek plates I'I, these lever plates being free for pivotal movement. They have a radius greater than that of the forward portions of the cheek plates, the latter being formed with body portions concentric with the sheaves and lying outwardly of the sheaves in a normal degree. At the lower parts the lever plates are connected by an interconnected stiifening lug 32, and at their upper parts by a cross pin 33, by which the two are secured rigidly in relation to each other. They have a roller 35, as dotted in the figure.

series of apertures 34 arranged concentrically beyond the cheek plates, in which a pin 35' is engageable, the apertures of one plate being alined with those of the other plate, so that the pin is supported transversely in the two lower plates. rlhis pin is removable and insertable in any opposed pair of apertures 34. On it there. is revoluble a roller 35, suiciently grooved to af,- ford a suitable track for a cable drawn over the adjacent sheave I6.

The lever plates at their outer parts extend over a radius of 170 degrees more or less, with respect to the pin l5, and, their partis of major radius are located principally at the front of the device, but extending between the upper extensions il of the cheek plates Il. At their upper and rearmost parts they are formed with slots 3S receiving the roller sleeves 24 therethrough. These slots extend in a suitable direction to permit the dog 2i to-be lifted by forward movement of the upper parts of the plates, due tothe wiping action ofthe rear sides of the slots 35 on the rollers of the pin 2.2.

In use, the block is engaged with a line in the familiar way, it being possible to anchor one end of a cable to the eye I4, while the cable is threaded back and forth in-and between another standard double sheave block and my block, in. the familiar way. The load would be attachedI to the other block, while my block is suspended by the hook il as required. The cable being threaded through my block from right to left as viewed in Figure 1, the terminal end of the cable would hang from. the near sheave, being carried-over the This is termed the haul line. As long as this iswithout substantial pull thereon, the roller 35 Willbe inthe upper position illustrated in Figure l, allowing the dog 2l to be held by a spring 30 in locking engagement with the line whichl is thus prevented from feeding through the block, and the load sustained by the tackle will be held to whatever position it has. been raised. When the outer end of the cable is pulled upon with sufficient force the opposition of the spring Si) tending to hold the dog engaged will be overcome, and by a downward pressure of the cable on the rollerl 35, moving the lever plates countercloclrwise, the-slots 35 bear the pin 22 forwardly and swing the dog 2i forwardly and upwardly so as to clear the cable. There must now be applied to the cable sufficient draft to sustain the load, or to hoistv it ori to allow it to lower properly. The cable may be allowed to be retracted by the load, while sufficient force is applied and maintained to keep the roller 35 depressed, but a quick release will-permit the pressure Von the roller 35 to be sufliciently relieved to permit the-spring 3U to return the dog to engaged position, stopping further descent of the load. Also, in case of a handline, for which my invention is especially desirable, if the line is swung to one side or the other, the cable will ride on the side of the groove of the roller, to frictionally engage the plate i?, which will draw the plates rearwardly at their upper parts, and

cause positive movement of the dog tolocking position again without shock or abrupt stoppage of movement.

This appliance is particularly useful in hoisting painters stages and chairs and the'like, as well as other loads, its application to the various uses being readily appreciated by those versed in the art from the foregoing.

In case it is desired to utilize the device as a simple block without my locking device, I have provided a link 4B, pivot-ed on the lower bolt i9, as a part of the lower washer 20, this link having an aperture in its outer end to receive the pin 35, at times, and being of a length to receive this pin when engaged through the lowermost pair of apertures 3l! and with the lever plates at their lowermost position.

The dog may be faced with suitable friction material 4l, if desired, as indicated in Figure 4, which may consist of hard, semi-hard, or resilient rubber or other appropriate material, according to the uses contemplated.

It should` be understood that While I have disclosedy a double sheave pulley, the invention is applicablev to others with more or fewer sheaves. Also only one of the sheaves of my article need be used if preferred so that it corresponds to a single sheave pulley.

While I have described particularlyY the details of: one specific embodiment of my invention, it will be understood that this is-by way of example only, and I do not regardthe invention as limited thereto. On the contrary, modification in the construction and arrangement of the elements may. be made in varying degree without departing from the spirit of the invention, within the scope of the appended claims.

I claim:

1. A sheave block comprising a frame, a sheave revoluble therein, a spring loaded dog mounted movably above a sheave having a path such that it may move into wedging engagement with a line on the sheave, a lever connected with the dog to raise the dog from operative position at times, said frame including parallel check plates beside the sheave, said dog being, pivoted outwardlyV of' the sheave between the plates, said lever consisting of ay member'pivoted beside the sheave, a roller on the lever lying across the plane of the sheave to receive thereover a line passing also over the sheave, said dog having a transverse pin therethroughl spaced from its pivot and said member of the lever being slotted to receive the end oi"v the pinsol that movement of the lever willmove the pin and dog for operation of the latter.

2. The structure ofl claim l in which said lever includes a part outwardly of and extending a substantial distance in the plane of oscillation of the lever, and having a plurality of mounting meansv spacedin a series substantially in the direction of said oscillation, and said roller having a .shaft alternatively engageable with said mounting means of the lever for the purposes described.

3. The structure of claim l in which said lever includes a part extended beside the dog and movable in the direction of operative movement of the dog, said dog having a lateral projection operatively connected with the said part of the lever and extended beyond, a rod swingably mounted thereon, and a spring seated on the frame and under compression against the outer end of the rod in a direction coincident with the direction of engaging movement of the dog.

MAGNUS P. PALSSON. 

